Toll board time signal circuit



April 29, 1958 A. H. BELLIVEAU 2,832,831

TOLL BOARD TIME SIGNAL CIRCUIT Filed July 14, 1953 p I w L IQ 70- INVENTOR. ALFRED H. BELLNEAU AT TY.

United States Patent Q TOLL BOARD TlME SIGNAL CIRCUIT Alfred H. Belliveau, Chicago, 111., assignor to General Telephone Laboratories, Incorporated, a corporation of Delaware Application July 14, 1953, Serial No. 367,843

18 Claims. (Cl. 1797.1)

The present invention relates to a system which automatically signals predetermined time intervals during the course of telephone toll calls.

In telephone toll callpractice it is customary to charge a certain rate for an initial period such as 3 or minutes, with additional charges for overtime periods such as 3, 2 or 1 minute. Upon initiation of toll calls, the calling parties frequently request the operator to advise them when the initial time period of their calls has expired, and also, perhaps, when they are in the overtime periods and when these periods expire. heavy burden upon the operator who may be handling numerous toll calls simultaneously.

This invention relates to a circuit devised to relieve the toll operator of this burden.

One object of the invention is to provide an improved and simplified system that will transmit signals at pre determined time intervals to parties making toll calls.

Another object is to provide a system that will provide time signals for parties making toll calls, without the attention of the operator.

An additional object is to provide an automatic system for transmitting time signals to toll callers, wherein the operator merely operates certain keys at the beginning of a call.

A further object of the invention is to provide an automatic system for signalling toll callers at the expiration of selected time intervals.

In this invention, the toll operator has access to a series of push buttons or keys, each of which designates a different time interval, for example, 5 minutes, 3 minutes, 2 minutes and 1 minute. When connections for a toll call are completed, the operator need only momentarily operate these buttons or keys in some desired combination, with the result that signal tones will be sent over the line after suchintervals of time as correspond to the button or buttons operated. If the 5 minute and the 3 minute buttons are pressed by the operator, a tone signal will be released automatically after 5 minutes; then a tone signal will be released every 3 minutes thereafter, until the I parties to the call are disconnected.

This is accomplished by a circuit which'employs a timing motor with cam-operated contacts and a chain of counting relays. The circuit employing the chain of counting relaysis novel in that the complete chain does not necessarily cycle for each time interval to be signalled. in other words, in the present embodiment which shows a chain of 5 pairs of counting relays, four pairs of relays, for example, may operate in succession in order to enable the signalling of one time interval, whereupon all operated relays of the chain release, and thereafter three pairs of relays, for example, may operate in succession to signal the end of a shorter time interval, release and repeatedly operate and release until the system is disconnected from theline.

The various objects and features of this invention can best be understood from a study of the description in connection with theaccompanying circuit drawing.

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The accompanying drawing shows the arrangement of the synchronous timing motor, the contacts operated thereby, the push buttons or keys controlled by the operator, the relays associated with the push buttons or keys, and the chain of counting relays employed in the preferred embodiment of this system.

In the present embodiment of this invention, the operator has access to a number of non-locking push buttons or keys, each representing a different time interval. In the drawing, keys 20, 3t), 40 and 50 designate respectively, intervals of 1, 2, 3 and 5 minutes.

A circuit as shown in the accompanying drawing is associated with each link circuit to which the toll operator has access. The circuit may be connected to the proper link in any desired manner such as by the operation of the link talk key or the switching relay shown in Patent No. 2,320,548, issued to I. H. Voss on June 1, 1943.

When the called station answers on a toll call, and caller requests the operator to signal, for instance, when the first 5 minutes have expired and thereafter when succeeding 3 minute overtime periods have expired, the operator operates the 5 minute key 50 and the 3 minute key 41}.

Relays 130 and will then be energized, and all of the contacts associated therewith will be operated. Upon Such requests cast a closing of contacts 132 on relay and 122 on relay 126), the respective relays will be locked and will remain energized after release or opening of the associated keys. The locking circuit for relay 130 includes contacts 132, 196 and 10 to ground on line L. The locking circuit for relay 126 includes contacts 1'76 and contacts 122, 113, 103 and It) to ground on line L. Contacts 10 are on a normally closed push key which serves as a correct key. Any error in setting by the operator may be corrected by op eration of this correct key and then the proper time in terval keys. Operation of the correct key causes the release of the entire circuit with the exception of relay 9%, whichis held operated through contacts 62 on the timing motor. The timing motor continues to receive current through contacts 94 on relay 90 and the motor cam continues to revolve. Corrrection of errors during the first minute of operation; i. e., during the first revolution of the motor cam, will not atfect the accuracy of the timing operation since none of the relays in the counting chain are actuated until the cam completes its first revolution.

' It is to be noted that the same restoring effect caused by operation of the correct key is produced'at the termination of a call. Line L is opened due to opening of a relay (not shown) connecting the signal circuit to the link just as it would be if contact 10 were opened. The effect is to restore the entire circuit to normal, ready for the next call.

The closing of contacts 133 and 123 closes the supply circuit to the l R. P. M. synchronous motor 6'1) which is thereupon started. The starting of the motor causes camoperated contacts 61 to open, and extinguish pilot light 7 0, indicating the circuit is in use. Cam-operated contact 62 will close, and cause relay hi to energize. This in turn provides another path of supply to motor oil through contact 94. The closing of contacts 93 energizes the upper winding of relay 90 through contacts 121 or 131, thereby keeping relay 9% energized. Contact 92 will close and thus a circuit is prepared to pulsing relay 80, and relay 81) will operate each time clock-operated contacts 61 close, i. e. every minute during operation of this circuit.

At the expiration of 1 minute, contacts 61 are closed by the timing motor 60 and relay 80 is operated for an instant.

Relay is caused to be operated *by means of a circuit completed through contacts 81 and 156. Contacts 151 close with operation of relay 150, but relay 155 is not operated because the coil is in effect shortedout by the ground at contact 81 whereby the same potential of voltage appears at each side of the coil. However, when pulsing relay 80 is deenergized and contacts 81 open, a closed circuit is completed from positive ground through contacts 121 and 131, in parallel, through contacts 199, 179, 169, through relay coil 155, contacts 151 and relay coil 150 to negative battery, thereby causing relays 150 and 155, now in series, to remain operated and to operate, respectively. Upon operation of relay 155, contacts 156 open and contacts 157 and 158 close, but do not afiect operation of the circuit at this time.

After the second minute, cam-operated contacts 61 again close, causing pulsing relay 80 to operate momentarily and to complete a circuit to relay 160 through contacts 81, 157 and 167. Contacts 161 are closed by operation of relay 160, but relay 165 will not operate until contacts 81 open, at which time a circuit is con pleted from positive ground through contacts 158, relay 165, contacts 161 and relay 160 to negative battery. Relay 160 will remain operated and relay 165 will operate. contacts 169 will not release energized relays 150 and 155, because contacts 169 are shunted by closed contacts 125 and 134, in parallel, closed due to earlier operation of relays 120 and 130, respectively.

After the third minute, cam-operated contacts 61 again close, causing momentary operation of pulsing relay 80.

Relay 170 is now caused to be operated due to a circuit which is completed through closed contacts 81, 157, 168, 126 and 135, 177 and relay coil 170. Upon the opening of contacts 81 of relay 80, relays 170 and 175 are both operated in series, from ground through contacts 158, relay 175, contacts 172 and relay 170. Operation of relay 175 and subsequent opening of contacts 179 will not release energized relays 150 and 155, because contacts 179 are shunted by contacts 141 which are closed due to the earlier operation of relay 130.

At the end of the fourth minute, contacts 81 are again caused to be closed by operation of pulsing relay 80, and a circuit is completed to energize relay 180 through contacts 81, 157, 168, 126 and 135, in parallel, 178, 140, 186 and coil 180. When pulsing relay 80 is deenergized, a circuit is completed from positive ground, through contacts 121 and 131 in parallel, contacts 199, coil of relay 185, contacts 181, relay coil 180 to negative battery, causing both relays 180 and 185 to be energized in series.

After the fifth minute, pulsing relay 80 is again momentarily energized by the closing of cam-operated contacts 61, contacts 81 close, and relay 190 is energized due to the closed circuit formed by contacts 81, 157, 168, 126 and 135, in parallel, 178, 149, 187 and 197. When relay 190 is energized, a closed circuit is completed from tone source through closed contacts 82, 162, 171, 191 and 139, and a tone signal is released to the link to indicate the end of the minute period.

On release of pulsing relay 80, relay 195, in series with relay 190, is energized through a circuit comprising contacts 158, relay 195, contacts 192 and relay 190.

Upon closing of relay 195, break contacts 196 are opened and 5 minute relay 130 is released. Break contacts 199 are also opened, and relays 150, 155, 180, 185 are deenergized. Release of relay 155 opens contacts 158, thereby releasing relays 160, 165, 170, 175, 190 and 195.

Only relays 120 and 90 now remain energized.

After the sixth minute, relays 158 and 155 operate as before. After the seventh minute, relays 160 and 165 operate as before. After the eighth minute, relays 170 and 175 operate as before. When relay 170 is energized, contacts 171 close and a closed circuit is formed to connect tone signal source through contacts 82, 162, 171, 129 and 138 to the link circuit. Thus, a signal has been released 3 minutes after the 5 minute signal was given. When relay 175 energizes, contacts 179 are opened and relays150 and 155 are released. This did Operation of relay 165 and subsequent opening of 1 not occur in the first sequence of operation because contacts 141, held closed by relay 130, shunted out contacts 179, and rendered their opening ineffective. Release of relay 155 opens contact 158 and relays 160, 165 and 170 and 175 are released. This cycle will then continue to repeat. a tone signal being released every 3 minutes until the toll call is completed.

When the toll call is completed, the release of a switching relay (not shown) which serves to connect the system to a link circuit, opens the circuit at conductor L and unlocks relay 120 which restores and removes locking ground at contacts 121 from the chain relays and all relays are restored. The release of relay 120 also removes locking ground from relay 90, which, however, will be held operated because of a circuit completed through the timing motor contacts 62 until the motor reaches its normal position in which contacts 62 are opened, whereupon relay will release and the pilot lamp 70 will again be lit.

To provide tone signals after 5 minutes and each 2 minute period thereafter, the operator presses keys 50 and 30. Relays 130 and are operated, and holding circuits for these relays are established through contacts 132, 196, and 10, and contacts 112, 107, 166 and 10, respectively. On the operation of relays 110 and 130, the timing motor 60 starts, a circuit having been completed by contacts 114 and 133, and the counting chain of relays is caused to run through a full sequence of operation as described before. After the fifth minute, the 5 minute tone is released to the link and relay and the entire counting chain of relays release as before. After the sixth minute, relays and again operate. After the seventh minute, relays and operate. When relay 160 operates, contacts 162 are closed, and a circuit from tone source through contacts 82, 162, 118, 128 and 137 is completed, thereby allowing a tone signal to go out to the link. When the pulse from relay 80 ceases, due to opening of contacts 81, and relay 165 is energized, contacts 169 are opened, and the circuit holding relays 150 and 155 are broken and they release. When relay 155 releases, relays 160 and 165 also release due to opening of contact 158. This cycle is repeated and a tone signal is released to the link each 2 minutes for the duration of the call.

To provide tone signals after the first 5 minutes of the call and each minute thereafter, the 5 minute key 50 and the 1 minute key 20 are operated. Relays 130 and 100 are thereby operated and holding circuits therefor are established through contacts 132, 196 and 10, and contacts 102 and 10, respectively. Timing motor 60 is started on operation of relays 100 and 130 due to closing of contacts 104 and 133. The counting relays operate as before to send a pulse of tone to the trunk after the first 5 minutes, whereupon relay 130 and the counting chain of relays restore.

After the sixth minute of the call, contacts 61 close and complete a circuit through closed contacts 92 and relay coil 80, to energize relay 80 and cause contacts 81 and 82 to close. When contacts 82 close, a circuit is completed from the tone source, through contacts 82, con tacts 108, contacts 117, contacts 127, and contacts 136 to the link circuit. Therefore, a tone signal is released to the link after the sixth minute.

The closing of contacts 81 after the sixth minute causes relays 150 and 155 to operate as before.

After the seventh minute, relay 80 is again energized momentarily and the closing of contacts 82 cause a signal again to be passed to the link circuit over the same path as for the sixth minute.

Operation of relay 80 and closing of contacts 81 after the seventh minute cause relays 160 and 165 to operate as before. Operation of relay 165 and the opening of contacts 169 causes a release of relays 150 and 155. Release of relay 155 and opening of contacts 158 will r tlcase relays 160' and 165. This cycle will 0ntinue for the duration of the call, i. e., the first two pairs of the relay chain will operate sequentially, release and reopcrate; a tone signal will be released in response to operation of each pair of chain relays, or more correctly, upon each operation of the pulsing relay 8! If the 3 minute key and the 2 minute key 31) are operated to signal expiration of 3 minute and each 2 minutes thereafter, relays 121) and are Operated and holding circuits therefor are completed through contacts 122, 176 and 1t and contacts 112, M7, 166 and 10, respectively. Motor 69 is started on closing oi contacts and 124, and as before, relays 15d and 155 respond to the first pulse of relay 8t relays 16d and 165 respond to the second pulse, and relays 17d and 175 respond to the third pulse.

On operation of relay 170, a closed tone signal circuit is completed through contacts 82, 162, 171, 129 and 130 and a signal is released after the 3 minute period.

When relay 175 is energized, contacts 179 open, and since shunting contacts 141 are not closed, the relays 15% and 155 are released. Release of relay 155 causes opening of contacts 158 and relays 161i, 165, 171) and 175 are also deenergized.

Release of relay 175 openscontacts 176 and relay is caused to be released.

Thereafter, in response to the fourth pulse of relay 80, relays 151 and 155 are operated. In response to the fifth pulse of relay so, relays 169 and 165 are operated as before. Closing of relay 169 closes contacts 162 which completes a circuit through contacts 82, 162, 118, 128 and 13 7 to connect tone source to the link circuit and a tone signal indicating the end of a 2 minute period is transmitted.

Closing of relay 165 opens contacts 169 and since neither shunting contacts nor 134 are now closed, the holding circuit to relays 15 and is opened and these relays are released. Release of relay 155 causes releasing of relay and and this cycle is reepated, i. e., the'first two pairs of chain relays operate sequentially, release, and then repeat; the tone signal is released only upon operation of the second pair of chain relays, or each 2 minutes.

If the 3 minute key 41) and the 1 minute key 21) are operated, relays 120 and ltltl operate, and the motor 60 is started. The chain of relays will pass tone signal to the link at the third pulse, thereupon releasing relay 120 and the operated relays of the chain, as before. Thereafter, only relays 150, 155, 160 and 165 will respond to the pulsing, and relay 31 will pass signal tone to the link at the end of each minute by way of closing of contacts 82, 108, 117, 127 and 136.

if the 2 and 1 minute keys, 3-0 and 2%, are operated, relays 110 and 100 operate and the timing motor 60 is started. The first two pairs of relays in the chain will operate in sequence and will release the tone signal to the link atthe second pulse of relay 80, by way of contacts 552, 162, 113, 128 and 137. At the end of the second pulse, relay 110 and relays 156, 155, 160 and 165 release. Relays 15), 155, 1651 and 165 continue to operate sequentially and release in response to further pulsing, and relay 81! will pass a signal tone to the trunk at the end of each minute, as before, through contacts 82, 108, 117, 127 and 136.

in the circuit heretofore described, any combination of two keys, each representing an individual time interval, may be operated, with the result that a tone signal will be transmitted once at the end of the longer of the two selected time intervals, and thereafter, repeatedly, on the termination of succeeding intervals of the shorter of the two selected time intervals.

Having described this invention in detail, what is desired to be protected by issuance of Letters Patent of the United States is as follows:

1. In a telephone system, a clock-operated switch, a plurality of manually operated keys representing unequal T5 time intervals, meanscontrolled by the operation of any two of said keys for operating said-clock-operated switch, a pulsing relay, means controlled by operation of said clock-operated switch for'operating said pulsing relay, a chain of counting relays, means controlled by the operation of said pulsing relay for sequentially operating said counting relays, an outgoing line, a source of tone signal, means controlled by said counting relays for connecting said source to said outgoing line at time intervals determined by the particular keys operated.

A for use in a telephone system, Which will automatically transmit audible signals at preselected time intervals, comprising a plurality of manually operated keys representing individual time intervals, :1 pulsing relay, clock-operated contacts for controlling said pulsing relay, means controlled by the operation of certain of said keys for initially operating said contacts, a chain of counting relays, means controlled by said pulsing relay for operating said chain of of counting relays sequentially, an outgoing line, a source of tone signal, means controlled by the operation of said counting relays for connecting said source to said outgoing line at time intervals determined by the particular ones of said keys operated.

3. Ina system for automatically transmitting audible signals to an outgoing circuit at preselected unequal time intervals, a plurality of keys designating available time intervals at which signals can be transmitted, a pulsing relay, cam'operated contacts for controlling said pulsing relay, means controlled by the operation of selected ones of said keys for initiating the operation of said cam-operated contacts, a chain of counting relays, means controlled by said pulsing relay for operating said chain of counting relays in a particular manner determined by theparticular ones of said plurality of keys operated, a source of tone signal, an outgoing circuit, means controlled by the operation of said counting relays for connecting said tone signal source to said outgoing circuit at time intervals deter mined by the selected ones of said plurality of keys.

4. In a system 'for automatically transmitting audible signals to an outgoing circuit at predetermined time intervals, a plurality of keys representing unequal time intervals, a plurality of relays controlled by respective ones of said keys, 2. pulsing relay, a revolving cam operating contacts for controlling said pulsing relay, a mechanism for driving said cam, means controlled-by operation of said relays for operating said mechanism, a chain of counting realys, means controlled by said pulsing relay for operating said counting relays sequentially, a source of tone signal, an outgoing circuit, and means for connecting said tone signal source to said outgoing circuit at time intervals determined by operated ones of said plurality of keys, said means comprising contacts of certain of said plurality of relays and contacts of certain of said counting relays.

5. In a system for automatically transmitting tone signals at predetermined time intervals to an outgoing circuit, a plurality of keys representing different time intervals, a plurality of relays controlled by respective ones of said keys, cam-operated contacts, a mechanism initially controlled by operated ones of said plurality of relays for driving said cam-operated contacts, a holding relay initially energized by said cam-operated contacts for continuing the operation of said mechanism, means controlled by the operation of certain of said plurality of relays for subsequently energizing said holding relay, a pulsing relay controlled by the operation of said cam-operated contacts, a chain of counting relays, means controlled by the operation of said pulsing relay for operating said counting relays sequentially, a source of tone signal, an outgoing circuit, means for connecting said tone signal source to said outgoing circuit at particular time intervals as determined by selected ones of said plurality of keys, said means comprising contacts of certain of said plurality of relays and contacts of certain ofsaid counting relays.

6. In a system for automatically transmitting audible signals at predetermined time intervals to an outgoing circuit, a plurality of keys which represent unequal time intervals, a plurality of relays controlled by respective ones of said keys, a set of contacts, a mechanism for operating said set of contacts, means operated in response to operated ones of said plurality of relays for initially operating said mechanism, a holding relay initially energized by said set of contacts and serving to continue the operation of said mechanism, said holding relay dependent for its continued operation upon the continued opera tion of at least one of said plurality of relays, a pulsing relay operated in response to operation of said set of contacts, a chain of counting relays, means whereby said counting relays are operated sequentially in respone to operation of said pulsing relay, a source of tone signal, an otugoing circuit, and means for connecting said tone signal source to said outgoing circuit at particular time intervals as determined by operated ones of said plurality of keys, said means comprising contacts of certain of said plurality of relays and contacts of certain of said counting relays.

7. In a system for automatically transmitting audible signals at preselected time intervals to an outgoing circuit, a plurality of keys representing unequal time intervals, a pulsing relay, contacts for controlling said pulsing relay, means whereby the operation of said contacts is initiated by operation of said keys, a chain of counting relays, means foroperating said counting relays sequentially in response to operation of said pulsing relay, a source of tone signal, an outgoing circuit, a circuit controlled by said counting relays and said keys for connecting said tone signal source to said outgoing circuit, and means whereby said circuit repeatedly connects said signal to said outgoing circuit when any combination of two of said keys is operated, once at the longer time interval and thereafter at the shorter time interval.

8. In a system for automatically transmitting audible signals at preselected time intervals to an outgoing circuit, a plurality of keys representing different time intervals at which the signal may be transmitted, said keys operable in any combination of two, a pulsing relay, contacts for controlling said pulsing relay, means whereby the operation of said contacts is initiated in response to operation of said keys, a chain of counting relays,

means for operating said counting relays sequentially, means whereby said last means is operated in response to operation of said pulsing relay, a source of tone signal, an outgoing circuit, means controlled by said counting relays and said keys for connecting Said tone signal source to said outgoing circuit, and means whereby said circuit transmits said tone signal once for the longer time interval, and thereafter repeatedly for the shorter time interval of the combination of two time intervals selected by operation of said keys.

9. In a system for automatically transmitting audible signals to an outgoing circuit at preselected time intervals, a plurality of keys representing unequal time intervals at which a time signal may be transmitted, and operable in any combination of two, a plurality of relays controlled by respective ones of said keys, a chain of counting relays, means controlled by the operation of certain of said relays for operating said counting relays sequentially, a source of tone signal, an outgoing circuit, means controlled by said counting relays and said selected keys for connecting said source of tone signal to said outgoing circuit, at time intervals determined by the operated ones of said keys.

10. In a system for automatically transmitting audible signals to an outgoing circuit at preselected time intervals, a plurality of manually operated keys representing unequal time intervals at which the signal may be transmitted, a plurality of relays, means whereby said relays are initially energized by associated ones of said keys, a pulsing relay, contacts for controlling said pulsing relay, means whereby the operation of said contacts is initiated by the operation of any two of said plurality of relays, a chain of pairs of counting relays, means whereby the first relay of each of said pairs is energized in response to operation of said pulsing relay, means whereby the second relay of each of said pairs is caused to be energized by the operation of said first relay and release of said pulsing relay, means whereby each of said pairs of relays operate sequentially, a source of tone signal, an outgoing circuit, a circuit controlled by the said first ones of said counting relays and said selected keys for connecting said source of tone signal to said outgoing circuit at predetermined time intervals, and means controlled by said pulsing relay for releasing said tone source from said outgoing circuit after each application thereof.

11. in a telephone signalling system, a plurality of keys representing unequal time intervals at which audible signals can automatically be transmitted to an outgoing circuit, each of said plurality 0 keys having an associated relay, a pulsing relay, contacts for controlling said pulsing relay, means whereby the operation of said contacts is initiated in response to the operation by said keys of any two of said associated relays, a chain of counting relays, means for operating said counting relays sequentially in response to operation of said pulsing relay, a source of tone signal, means controlled by the operation of said relays and said keys for connecting said tone signal source to said outgoing circuit at intervals of time determined by operated ones of said keys, and means for deenergizing all of said plurality of relays which may be operated to restore the system to a normal condition ready for another operation.

12. In a system for automatically transmitting audible signals to an outgoing circuit at predetermined time intervals, a manually operated selection means which represents a plurality of unequal time intervals, a plurality of relays controlled by respective selections of said selection means, a pulsing relay, contacts for controlling said pulsing relay, a mechanism for operating said contacts, means controlled by operation of said relays for operating said mechanism, a chain of counting relays, means controlled by said pulsing relay for sequentially operating said counting relays, a source of tone signal, an outgoing circuit, and means for connecting said tone signal source to said outgoing circuit at time intervals determined by preselectiou of said selection means, said connecting means comprising contacts of certain of said plurality of relays and contacts of certain of said counting relays.

13. A time signal arrangement for use in a telephone system wherein connections are completed and wherein charges are made for the length of time the connection is held, a tone source, a plurality of keys, one for each different time interval for which a charge may be assessed, means automatically controlled by the operation of any pair of said keys corresponding to an initial and a subsequent time interval for applying said tone to a connection at the end of said initial time interval and again at the end of said subsequent time interval.

14. A time signalling system for use in a telephone system wherein connections are completed and wherein charges are made for the length of time the connection is held, comprising a tone source, a plurality of keys designating time intervals for which charges may be assessed, a series of counting relays, means controlled by operation of any pair of said keys to cause sequential operation of said couting relays, a certain number of said relays operated to connect said tone source after a time interval determined by one key of said operated pair of keys, and only a lesser number of saidrelays operated to connect said tone source thereafter at the end of a time interval determined by the other key of said operated pair of keys.

15. In a system for automatically transmitting audible signals at predetermined time intervals, a manually operated means for selecting time intervals at which the signal is to be transmitted, a clock operated switch controlled by an operation of said selecting means, a chain of relays, means controlled by said clock operated switch for operating a certain number of said relays,as determined by the operation of said selecting means, sequentially and in cyclic repetition, a source of tone signal, means for transmitting said tone signal on termination of each cycle of operation of said chain of relays.

16. In a time signalling system, an outgoing circuit, a tone source, a chain of counting relays, means for manually marking said chain in accordance with any two of a plurality of different time intervals, means controlled by the operation of said marking means for causing said chain to count a period of time equal to the greatest marked time interval, means for then again operating said chain to count a period of time equal to the lesser marked time interval, and means controlled by said counting chain for connecting said tone source to said outgoing circuit after each interval has been counted.

17. An elapsed-time signalling device consisting of a plurality of manually operated keys, one for each of a plurality of unequal time intervals, means controlled by the operation of said keys for presetting said device to measure any pair of said time intervals, at timing mechanism, means actuated by said keys to start said timing mechanism, a source of signal tone, an outgoing circuit,

means initiated by said timing mechanism to connect said source of signal tone to said outgoing circuit at the end of the longer preset time interval, again after the shorter preset time interval, and thenceforth after each successive passage of the said shorter time interval, another manually operated key, means responsive to the operation of said last-mentioned key and other of the time interval keys for signalling different time intervals than those originally set.

18. An elapsed-time signalling device consisting of a plurality of manually operated keys representing unequal time intervals, a timing mechanism, means actuated by operation of certain of said keys to start said timing mechanism, a source of signal tone, means initiated by said timing mechanism to connect said source of signal tone to an outgoing line at time intervals determined by the particular keys operated, another manually operated key, means responsive to operation of said last mentioned key and reoperation of said time interval keys, to correct errors in time intervals previously set by said keys without disturbing the accuracy of the timing operation already in progress.

References Cited in the file of this patent UNITED STATES PATENTS 2,094,060 Busch Sept. 28, 1937 2,112,375 Mead Mar. 29, 1938 2,115,280 Perlman Apr. 26, 1938 2,488,797 Baker Nov. 22, 1949 2,492,381 Dunning Dec. 27, 1949 2,533,677 McCreary Dec. 12, 1950 

